The aerosol technique is based on the use of insecticides dissolved in a volatile fluid, the solution being forced into the atmosphere through a fine aperture so that it is dispersed in the form of extremely line droplets. Special aerosol canisters utilise a gas under pressure to carry theinto the area to be treated.
Various insecticides and, to a lesser extent, fungicides, are used in this way, mainly in the. They include Pyrethrin, BHC and nicotine. Aerosols are also employed in the disinfestation of warehouses, food stores etc., and certain proprietary fly sprays for use in houses are frequently made up in this form.
AESCULUS, HORSE CHESTNUT or BUCKEYE T. Hardy, deciduous trees easily cultivated in any soil. The common horse chestnut (Aesculus hippocastanum) is a very rapid grower, ultimately reaching 70—100 ft. The whiteare splashed with red and yellow and are followed by clusters of green, prickly fruits enclosing the schoolboy’s ‘conker’. The tree does not usually start to fruit until about 20 years old. Sheep, cattle and deer (but not horses) eat the fruits. There is a double-flowered form which does not fruit.
The timber is white and soft and was at one time used for milk pails. The even grain takes a good polish and is consequently sometimes used in cabinet-making. Although not very durable, chestnut can be employed for rose pillars and pergolas.
The red or pink horse chestnut (A. camea or rubicunda) produces soft rose-coloured flowers growing to about 50 ft., A. carnea briotii having deeper-coloured flowers borne in larger clusters. The Himalayan or Indian chestnut (A. indica) grows to about the same height as the common horse chestnut with similar-coloured blooms, but the panicles of flower are twice as long and appear 4—6 weeks later.
A. parviflora (macrostachya) is suitable for small gardens as it only grows to about 10 ft. The white flowers appear in late July. Most chestnuts are easily propagated by, self-sown being very frequent. A. parviflora can be increased in March by detaching and replanting the suckers which appear at soil level.
AETHIONEMA, STONE CRESS or LEBANON CANDYTUFT Very decorative perennials, 6—12 in. high, for sunny rockeries or dry walls, flowering from early summer onwards. They prefer a light, limy soil which must be well-drained. Recommended kinds are: the deep pink Aethionema Warley, the white A. iberideum and the rose-pink A. pul-chellum.
Cut back the growths slightly after flowering. Cuttings of half-ripened wood are taken in July.